That is the typical explanation, and there are others, but diving into the deep psychological reasons for things is always hit or miss. We can never know what an initial trigger may be. In my case I am a handsome guy who has always gotten lots of attention from women going back to Michelle and Cindy chasing me around the playground in 1st grade trying to kiss me. To this day in middle age I still get lots of female attention even from younger women. On top of that I have always been a stud in the bedroom. Usually performing for hours and lacking no confidence whatsoever. I have had many women tell me I should be a porn star. That being said the strongest fantasy I have had for years and years now is having a wife that cheats on me. The scenarios are endless but her doing it behind my back is extremely stimulating and I want to find out or suspect it’s happening and ravage her sexually afterwards. I want her to jump back and forth between having sex with me and other men. Having a secret fuck buddy would drive me wild. I myself have no idea where this comes from but my strongest thought is competition. Sperm competition is a deep instinctual trait in men. I always want the other guy to be great in bed and have a big cock. None of this comes from me feeling inadequate. In fact I worry that there are too many guys not as good as me and it might be hard to find a lot of nice studs.
I'm not trying to generalise or oversimplify the trigger mechanism of the cuckold fetish, but there is definitely a repetitive pattern between people who are into this. In the greatest percentage, the common ground between cuckolds is past cheating experiences. However, I will agree with you that there are cases where the event or emotional state that triggered this kink is not clear.
My previous comment was trying to picture the evolution of the default cuckold persona and the journey some of us took from our teenage years and the first red flags to the point of realization and acceptance of our weak male nature. An experiential, hard but sincere acceptance that does not necessarily implying any homosexual tendencies as some might think.
Although, I wouldn't go as far as you, because in 1st grade when Michelle and Cindy were chasing you around the playground for an innocent kiss, I would expect you to know that this has nothing to do with a little boy's physical attraction. Sorry for being a bit cynical, but when you hear a man opening an argument with such a absurd statement, you can't be anything but negatively biased when he portraits himself as the absolute stud. To be fair though, and regardless if you seem to slightly exaggerate about yourself, there is no doubt that there are many highly attractive, well-endowed men out there that are still obsessed with cuckoldry or seek pleasure from being infidelity victims.
But guess what? Even a good-looking man with a more than average cock can have secret or subconscious insecurities (social & personality, career & financial stability, jealousy & possessiveness, body image, validation issues, etc) that prevent him being the typical "alpha". Unlike other cuckolds, he's more extroverted, he has moderate to high success with women, he's sexually adequate, but he lacks those elements to fuck a woman's mind, and keep her by his side. On the opposite side, a man who has a brilliant mind and personality is capable to mentally stimulate and attract a woman but the soon his insecurities about his dicklet will put an end in his ambitions. Out of the two men, the first might have more success in casual sex, but the second one is widely regarded as marriage material. At the end of the day though, and since they're equally regarded as highly-cheatable for obvious reasons, their brain will react similarly to their own moments of distress, and generate the cuckold germ.
My advise is to stop worrying about be hard to find studs like you around Chicago area. Such bolt statements are not only disrespectful to BBCs of this site, but they sound equally ridiculous to all white husbands who had the honour to hold their woman's hand while a BBC was smashing her ass like there was no tomorrow.
Sperm competition is definitely a great motive to share your wife with another assertive man, but I doubt is the source of your vivid cheating fantasies. I'm not sure what kind of insecurities you subconsciously have as a man, but if you manage to remove the filter of delusion in which you currently see the world through, and re-evaluate yourself to its core, you will get the answer and what feeds your guilty obsession.
The real question is: does your male ego allows you the room for such a fateful revelation? Cause if it does, and you accept your weak side of yourself your limitations and insecurities, then your wish to watch your wife with a "better" man has great chances to be fulfilled like a sweet-bitter curse with the universe conspiring for it.